A safety of subsea oil and gas pipeline is a key technology of the offshore oil and gas exploration technology. Comparing with a land oil and gas pipeline, the subsea oil and gas pipeline is more digamous for environment and has more complicated working condition, so that routine inspecting and maintaining is significant for the safety of subsea oil and gas pipeline.
An inner detecting device for subsea oil and gas pipeline must have a good travel capability within the pipeline which has a complicated structure, for example the pipeline has vertical sections connected to the oil platform, and the bended connector of the oil platform has a turning radius of 1.5 D, so that the deformability of the inner detecting device corresponding to the inner wall of the pipeline is important for the inner detecting device to travel within the pipeline smoothly.
Conventional leakage detecting devices for the oil and gas pipeline generally have fixed magnetized shaft body and odometer wheel system, for example a high definition mechanical system of pipe leakage detectors are described in Chinese Pat. No. 200710118862.4. Due to structures of the fixed magnetized shaft body and odometer wheel system, the conventional leakage detecting device has a poor deformability, in other words, the minimum radial and axial dimensions of the leakage detecting device too large to be adapted to travel within the pipeline which has the vertical sections and less turning radius.